The present invention relates to a lens-fitted film unit, and more particularly, to a lens-fitted film unit which makes it possible to photograph under an appropriate exposure.
Lens-fitted film units which are relatively inexpensive are available on the market, which makes it possible to enjoy photographing at ease without using an expensive camera. A user purchases a lens-fitted film unit with a built-in film, and carries it into a certain photofinisher after photographing for a prescribed number of exposures.
In the photofinisher, a film is separated from a camera main body of the lens-fitted film unit thus carried in, then, a first cycle print is made from the film in general, and a negative film and a photograph representing the print are returned to the user. On the other hand, the camera main body is collected to a prescribed factory for recycling.
Incidentally, in the case of this lens-fitted film unit under the condition of recycling, it is necessary to keep its cost low, and a camera of this kind is provided with only required and minimum functions. Therefore, even under the photographing conditions which are not problematic for ordinary cameras, troubles are sometimes caused. An example of these troubles is shown below.
For example, since an ordinary lens-fitted film unit is not equipped with a photometry means, even in the case of a lens-fitted film unit with an electronic flash unit, a photographer must decide whether to use the electronic flash unit or not. Accordingly, in a lens-fitted film unit of this type, there is provided a manual operation switch with which an electronic flash unit is caused to emit light. However, this switch is designed to be turned on and turned off by the movement of a sliding member, for example, and once the sliding member is slid to the ON side, an electronic flash circuit continues charging a capacitor unless the sliding member is returned to the OFF side. When a photographer forgets to turn off the electronic flash switch, wasteful charging is continued, resulting in a problem that electronic flash photographing is impossible because of a battery which is dead when it is used for actual photographing. Since it is impossible for a photographer to replace a battery in the case of an ordinary lens-fitted film unit, the problem mentioned above is extremely serious.
Further, since a photographer often does not feel the gloom, due to a characteristic of human eyes, even when luminance of field is lowered to a certain extent, the photographer believes that photographing can be conducted sufficiently even under the state of low luminance like that under a fluorescent lamp for interior illumination, and photographs without using electronic flash emission. In that case, there is caused a problem of the so-called under exposure, and necessary image quality can not be obtained.